Oilpan: move WorkerGlobalScope to oilpan's heap.

Source/core/workers/WorkerThread.cpp

Index: Source/core/workers/WorkerThread.cpp
diff --git a/Source/core/workers/WorkerThread.cpp b/Source/core/workers/WorkerThread.cpp
index 7d6efc7e0b26cba91178b60b26e619b6bdb76e67..ce222b591d0fe3b659ecda6255d87f2dd003007e 100644
--- a/Source/core/workers/WorkerThread.cpp
+++ b/Source/core/workers/WorkerThread.cpp
@@ -141,6 +141,7 @@ void WorkerThread::workerThread()
 
     // The below assignment will destroy the context, which will in turn notify messaging proxy.
     // We cannot let any objects survive past thread exit, because no other thread will run GC or otherwise destroy them.
+    m_workerGlobalScope->detach();
     m_workerGlobalScope = nullptr;

[haraken, 2014/02/26 02:39:34]

Shall we change m_workerGlobalScope to RefPtrWillBePersistent?

We might want to remove all RefPtr<WorkerGlobalScope>s except for a case where
WorkerGlobalScope is treated as EventTargets. "RefCounted"GarbageCollected
should be just for EventTargets.

[sof, 2014/02/26 06:29:42]

Makes sense to do that (but I didn't want to increase the footprint of this CL
more than needed.) Now done.

 
     // Cleanup thread heap which causes all objects to be finalized.